During manufacturing a flat panel display device, for the reason of process, a defect, especially a broken line defect, often occurs after a device is packaged.
Currently, in order to solve the problem of the broken line, a method for repairing the broken line that forming a circuit by means of laser welding is used. Taking a thin film transistor (TFT) liquid crystal display (LCD) as an example, as shown in FIG. 1 and FIG. 2, a broken line region 7 exists in an effective display region 2 on a glass substrate 1 before repairing. A first repairing line 3 is disposed on a scan line metal layer, and a second repairing line 5 is disposed on a signal line metal layer. The first repairing line 3 is located in the same layer with a repairing circuit of a driving circuit 6. The direction of an electric current 8 in the broken line region is shown as the dashed arrow in FIG. 1. The electric current is cut off at the broken line region 7, as a result of which there is no electric current passing through the lower part of the signal line 50 under the broken line region 7.
In a repairing process after a cell process, two ends of the signal line 50, where the broken line region 7 is located, overlap with active layers 4, and two ends of the second repairing line 5 overlap with active layers 4 are both melted to form melting regions 9 by using laser beams, so as to enable the signal line 50 to be connected with the first repairing line 3 and the second repairing line 5 and form a circuit that makes other parts of the metal line except the broken line region 7 be connected, as shown in FIG. 3 and FIG. 4. The laser melting regions 9 enable the electric current which should have passed through the upper half part 71 of the broken line region 7 to pass through the first repairing line 3, the driving circuit 6 and the second repairing line 5 along the direction of the dashed arrow and reach the lower half part 72 of the broken line region 7, which ensures that there is electric current passing through the parts of the signal line both above and under the broken line region 7, i.e., there is electric current passing through other parts of the signal line 50 except the broken line region 7.
However, in the circuit formed by this method, due to a load effect of resistances and capacitances on the driving circuit 6, the scan line metal layer and the first repairing line 3, delay phenomenon will occur on the signal, resulting in that the signals in the upper half and the lower half of the repaired metal line are different which may cause bad influence to the repairing effect.